1. Field of the Invention
This invention relates to devices for holding bowling balls while finger holes and weighting holes are drilled in the ball. In particular, the present invention relates to vacuum chucks used to hold a bowling ball steady during drilling.
2. Description of the Prior Art
Common mechanical vices are awkward and difficult to use for holding heavy, round objects such as bowling balls, while drilling. An improvement over mechanical vices is the vacuum vice, shown for example, in U.S. Pat. No. 5,173,016. Such conventional vacuum vices typically include a vacuum chamber and a hard rim which makes a seal with the bowling ball. It is difficult to make a vacuum tight seal between the hard surface of the bowling ball and the hard rim, so additional sealing techniques, such as a movable, external soft sealing ring, have been used to reduce leakage. Such conventional vacuum vices are not completely effective when there are imperfections in the surface of the bowling ball. For example, nicks or engraving in the ball break the seal between the ball and the prior art vacuum vice, thus reducing its ability to hold the ball effectively.
What is needed is a vacuum vice which can form a vacuum tight seal while holding a bowling ball in an exact position determined, for example, by a hard rim, in spite of imperfections in the surface of the bowling ball.